如图所示,理想变压器原、副线圈的匝数比为1:10,接线柱a、b接在电压为u=10

题型:选择题

问题:

如图所示,理想变压器原、副线圈的匝数比为1:10,接线柱ab接在电压为u=10sin100πtV的正弦交流电源上,R1为定值电阻,其阻值为100Ω,R2为用半导体热敏材料制成的传感器.下列说法中正确的是

A.ts时,ab两点间电压的瞬时值为5V

B.ts时,电压表的读数为100V

C.在1min内电阻R1上产生的热量为6000J

D.当R2的温度升高时,电压表示数不变,电流表示数变大

考点:变压器电压、电流、电功率与匝数的关系
题型:选择题

一品红温室栽培时,室温应保持在()以上。

A.10℃

B.15℃

C.20℃

D.25℃

题型:选择题

风湿性心脏病主动脉瓣狭窄时,下列各项表现中不正确的是

A.主动脉瓣区喷射性收缩期杂音
B.主动脉瓣区第二音减弱
C.脉压小、脉搏细弱
D.左心室明显扩张
E.左心室肥厚

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晓阳理发店在国庆六十周年那天正式营业,只有晓阳一个理发师,却同时来了4位顾客,给甲理发需要5分钟,给乙理发需要15分钟,给丙理发需要25分钟,给丁理发需要20分钟,晓阳应该按顺序安排,才能使四位顾客等候的时间总和最少。[ ]

A.甲、乙、丙、丁    

B.甲、乙、丁、丙 

C.丙、丁、甲、乙    

D.甲、丁、乙、丙

题型:选择题

关于胃癌下述哪项不常见()

A.增生性胃息肉不易发生癌变

B.胃癌最早发生于胃体小弯部

C.早期胃癌患者也可有淋巴结转移

D.弥散型胃癌为恶性程度最高的胃癌

E.胃癌扩散以淋巴转移最常见

题型:选择题

What is it that brings about such an intimate connection between language and thinking Is there no thinking without the use of language, namely in concepts and concept combinations for which words need not necessarily come to mind Has not every one of us struggled for words although the connection between " things " was already clear
(46)We might be inclined to attribute to the act of thinking complete independence from language if the individual formed or were able to form his concepts without the verbal guidance of his environment. Yet most likely the mental shape of an individual, growing up under such conditions, would be very poor. Thus we may conclude that the mental development of the individual and his way of forming concepts depend to a high degree upon language. This makes us realize to what extent the same language means the same mentality. In this sense thinking and language are linked together.
What distinguishes the language of science from languages as we ordinarily understand the word How is it that scientific language is international (47)What science strives for is an utmost acutencess and clarity of concepts as regards their mutual relation and their correspondence to sensory data. As an illustration, let us take the language of Euclidean geometry and Algebra. They manipulate with a small number of independently introduced concepts, respectively symbols, such as the integral number, the straight line, the point, as well as with signs which designate the fundamental concepts. This is the basis for the construction, respectively definition of all other statements and concepts. The connection between concepts and statements on the one hand and the sensory data on the other hand is established through acts of counting and measuring whose performance is sufficiently well determined.
(48)The super-national character of scientific concepts and scientific language is due to the face that they have been set up by the best brains of all countries and all times. In solitude and yet in cooperative effort as regards the final effect they created the spiritual tools for the technical revolutions which have transformed the life of mankind in the last centuries. Their system of concepts has served as a guide in the bewildering chaos of perceptions so that we learned to grasp general truths from particular observations.
What hopes and fears does the scientific method imply for mankind I do not think that this is the right way to put the question. Whatever this tool in the hand of man will produce depends entirely on the nature of the goals alive in this mankind. Once these goals exist, the scientitle method furnishes means to realize them. Yet it cannot furnish the very goals. (49)The scientific method itself would not have led anywhere, and it would not even have been born without a passionate striving for clear understanding.
Perfection of means and confusion of goals seem—in my opinion—to characterize our age. (50)If we desire sincerely and passionately the safety, the welfare and the free development of the talents of all men, we shall not be in want of the means to approach such a state. Even if only a small part of mankind strives for such goals, their superiority will prove itself in the long run.

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